﻿<p>The <em>IfcSphere</em> is a Construction Solid Geometry (CSG) 3D primitive. It is a solid where all points at the
surface have the same distance from the center point. The inherited <em>Position</em> attribute defines the
<em>IfcAxisPlacement3D</em> and provides:</p>
<ul>
<li><em>SELF\IfcCsgPrimitive3D.Position</em>: The location and orientation of the axis system for the
primitive.&nbsp;</li>
<li><em>SELF\IfcCsgPrimitive3D.Position.Location</em>: The center of the sphere.</li>
<li><em>SELF\IfcCsgPrimitive3D.Position.Position[3]:</em> The z axis points at its positve direction towards the north
pole, and by its negative directions towards the south pole.</li>
</ul>
<p>&nbsp;</p>
<table summary="illustration">
<tr>
<td><img src="../../../figures/ifcsphere-layout1.png" border="0" height="300" width="400" alt="sphere"></td>
<td><blockquote class="example">EXAMPLE&nbsp; Figure 3 illustrates geometric parameters of the sphere. The sphere is positioned within its own placement
coordiante system relative to the object coordinate system. The origin is the center of the sphere.</blockquote>
</tr>
<tr>
<td>
<p class="figure">Figure 3 &mdash; Sphere geometry</p>
</td>
</tr>
</table>
<blockquote class="extDef">NOTE&nbsp; Definition according to ISO/CD 10303-42:1992<br>
A sphere is a CSG primitive with a spherical shape defined by a centre and a radius.</blockquote>
<blockquote class="note">NOTE&nbsp; Entity adapted from <strong>sphere</strong> defined in ISO
10303-42.</blockquote>
<blockquote class="history">HISTORY&nbsp; New entity in IFC2x3.</blockquote>
<p class="use-head">Texture Use Definition</p>
<p>Textures are aligned facing upright with origin at the back (+Y direction) revolving counter-clockwise. Textures are
stretched or repeated to the extent of the circumference at the equator according to RepeatS and RepeatT.</p>
<p>Figure 4 illustrates default texture mapping with a clamped texture (RepeatS=False and RepeatT=False). The image
on the left shows the texture where the S axis points to the right and the T axis points up. The image on the right
shows the texture applied to the geometry where the X axis points back to the right, the Y axis points back to the
left, and the Z axis points up.</p>
<table summary="texture" class="gridtable">
<tr>
<td><img src="../../../figures/ifcsphere-texture.png" alt="texture"></td>
</tr>
<tr>
<td>
<table summary="texture" width="512" class="gridtable">
<tr valign="top">
<th>Side</th>
<th>Normal</th>
<th>Origin&nbsp;X</th>
<th>Origin&nbsp;Y</th>
<th>Origin&nbsp;Z</th>
<th>S&nbsp;Axis</th>
<th>T&nbsp;Axis</th>
</tr>
<tr valign="top">
<td>Side</td>
<td>+Y</td>
<td>0</td>
<td>+Radius</td>
<td>0</td>
<td>(-X, then curving counter-clockwise)</td>
<td>(+Z, then curving towards top)</td>
</tr>
</table>
</td>
</tr>
<tr>
<td>
<p class="figure">Figure 4 &mdash; Sphere textures</p>
</td>
</tr>
</table>